Process of removing colloidal suspensions from vegetable oils



Patented Jan. 21, 1 941 a v V UNITED sT'ATEs PATENT oFFici: 5

PROCESS REMOVING COLLOIDAL SUS- PENSIONS FRO M VEGETABLE OILS RalphH.Fash, Fort Worth, Tex., assignor to Anderson, Clayton & Co., ajoint-stock association, Houston, Tex.

No Drawing. Application October 13, 1938,

Serial No. 234,841 i 4 Claifms. (01. 260-422) I i This invention relatesto the removal of 001- the stateof dispersion of the colloidal material'loidal suspensions from non-aqueous liquids. which is to be removed ischanged so as to render The invention'is especially suitable for there-. it capable of being acted upon more efficiently fining. ofnon-aqueous substances such as oils, by any other colloid which may beused inthe 5 and, as illustrating one important application of refiningprocess.

the process, the removalof coloring matterfrom It has now beenascertained that the colloidal 5 vegetable oils, asfor exarnple, cottonseed,.soya coloring matter is present in the oilin various bean, andpeanut oils, willbe described. states of dispersion, and that whichremains in In refining vegetable oils, the present practice the oilafter oneor more refining operations is 10 is to add a large excess ofcaustic alkali for the that which is the most highly dispersed. Whilepurpose of neutralizing the free fatty acids presthe major portion ofthe colloidal material is ent in the crude product, and to substantiallyremoved in the first refining operation,reven reduce the color of theoil and remove undesirable where the ordinary soap colloid is theremoving constituents. The soap stock, togetherLWiththe agent, greatdifficulty is experienced in removing coloringmatter, are then separatedfrom the oil the very highly dispersed colloidal material which 15 bysettling or by centrifuging, orin any other conremains in the oil afterone or more refining ventional manner. Frequently, the'reduction inoperations, due to the extremely high dispersion color of the oilresulting from a single refining of the colloid. g i operation isinsufiicient and it has been theprac- I have found that the dispersionof the coltice to re-refine the oil in a similar manner one loidalmaterial which isto be removed can be 20 or more times. In manyinstances, the color cansubstantially reduced by exposing the oil,prefnot be reduced to the desired point without exerably after apreliminary refining operation, to cessive refining losses due to thereaction of the the action of radiant energy. The radiant energy alkaliwith the oil to form sOapQ tends to agglomerate the colloidal materialwhich 5 As a result of extensive investigation, I have is to be removedand render it capable of being ascertained that the coloring matter inthe oil acted upon by the colloid which is used in a subis present as anelectrically charged colloidal sequent refining operation. suspension.It has long been known that oil may be bleached While it was formerlybelieved that the reby the action of sunlight or ultra-violet light,

moval of the coloring matter by the caustic alkali but this bleachingeffect is temporary and the 3 was due to the solvent effect of thelatter, a more color will return. acceptable theoretical explanation ofthe removal Since the true effect of the sunlight or ultraof thecoloring matter is based on the hypothesis violet rays was notappreciated, the treatment that the colloidal coloring matter iselectrically with radiant energy is not at the present time recharged,and, in the treatment of the oil with garded as being of value in theproduction of 5 alkali colloidal soap is formed, which soap colloid, a,permanently bleached oil. However, I have being negatively charged,tends to neutralize the found that if the oil which has thus been actedcollo dal materia W iCh is po v y d. upon is re-refined either by theconventional As described in my copending application Sealkali treatmentor any other refining treatment 40 rial No. 234,840, filed October 18,1938, I have which utilizes colloids, before the colloidal color- 40discovered thata greater reduction in color with ingmatter has had anopportunity to become less refining loss can be obtained by utilizing adispersed, a very substantial and permanent rehighly dispersednegatively charged colloid, thus duction in color is obtained.

overcoming the relative inefliciency of the pres-- The radiant energywhich I prefer to use is ent practices, which is due to the fact thatthe that which has a shorter wave length than yelsoap colloid which isformed isnot highly dislow light, or in other words, having a wavelength parsed and does not as satisfactorily bring about less than 0.535micron. The action of yellow light electrical neutralization andprecipitation of the is neutral in this respect, and the action of rayscolloidal material whichis to be'removed. having a longer wave length,as for example, red While the invention described in my copending rays,increases the stability of the suspension. 50 application above referredto, is concerned with It is therefore desirable, particularly when usingthe utilization of a more highly dispersed colloid sunlight, to filterout the rays having a wave which will act upon the colloidal material tobe length longer than 0.535 micron. It will, thereremoved, the presentinvention, on the .other fore, be understood that by the term radianthand, relates to a method of refining whereby energy as used in thespecification and in the 55 appended claims, I refer to radiant energyhaving a wave length less than 0.535 micron.

It has also been found that the shorter the wave length of the radiantenergy which is used, the better the results which are obtained.

The following examples are illustrative of the preferred procedure: Inall of these examples, an oil which had been refined to a color ofyellow, 13.2 red was used.

A small quantity of 13.2 red oil was placed in a Pyrex dish, the depthof the oil being elevensixteenths of an inch. A 445-610 watt Cooper-Hewitt lamp was directed at the exposed surface of the oil at a distanceof three and one-half inches, and the oil was exposed to the ultravioletrays for ten minutes. During the exposure, the oil was agitated with astirring rod. Within an hour, the oil was re-refined and the color wasreduced to 35 yellow, 9.8 red.

A second experiment was carried out, starting with another sample of the13.2 red oil having a depth in the dish 'of about one-sixteenth of aninch, and the time of exposure was reduced to five minutes. There wasthus produced an oil which upon re-refining possessed a color of 9.5red.

The above results are to be compared with the results obtained byre-refining a sample of the same 13.2, red oil without exposure toradiant energy, which gave a color of 35 yellow, 10.3 red.

As illustrating the efi'ect of X-rays, a small quantity of 35 yellow,12.4 red refined oil having a depth of approximately one-half inch, wasex posed for ten minutes at a distance of four and one-quarter inches tothe action of X-rays. The total Roentgen units used in the ten minuteswas 5850. Within an hour, this oil was re-refined and the color wasreduced to 35 yellow, 8.3 red.

The results produced by the use of the X-rays are to be compared withthe fact that the same oil re-refined without exposure to radiant energygave a color of approximately 10.3.

In commercial practice, the oil may be more efficiently treated bysubjecting the oil, in the form of a thin film or spray, to theinfluence of the radiant energy.

It 'will be apparent that other rays having various wave lengths lessthan 0.535 micron may also be used, and the invention is not to beregarded as limited by the foregoing examples.

I claim:

1. The process of refining vegetable oil which consists in removing alarge proportion of colloidal material, subjecting the oil to the actionof radiant energy having a wave length of less than 0.535 micron toreduce the dispersion of the remaining colloidal material and removingthe colloidal material, the dispersion of which has been reduced.

2. The process of refining vegetable oil which consists in subjectingthe oil to a preliminary refining operation, then subjecting the oil tothe action of radiant energy having a wave length less than that ofyellow light to reduce the dispersion of the remaining colloidalmaterial and removing the colloidal material, the dispersion of whichhas been reduced.

3. The process of refining vegetable oil which consists in removing alarge proportion of colloidal material, subjecting the oil to the actionof ultra-violet rays to reduce the dispersion of the remaining colloidalmaterial and removing the colloidal material, the dispersion of whichhas been reduced.

4. The process of refining vegetable oil which consists in removing alarge proportion of colloidal material, subjecting the oil to the actionof X-rays to reduce the dispersion of the remaining colloidal materialand removing the colloidal material, the dispersion oi! which has beenreduced.

RALPH H. FASH.

